DE1075566B - Adsorption process for the purification of technical hydrogen and a suitable device for carrying it out - Google Patents

Description

GERMAN

The invention relates to an adsorption process for the purification of technical hydrogen for the purpose of production of high-purity hydrogen, which is practically free from carbon monoxide, oxygen and carbon dioxide with only a minimum number of treatment and purification stages required, which are specified in a suitable device is carried out.

Hydrogen is made technically through water electrolysis, the decomposition of water vapor with hot iron or iron oxide, thermal or catalytic cleavage of hydrocarbons, conversion of Hydrocarbons with water vapor, gasification of solid carbonaceous substances with water vapor and oxygen, catalytic conversion of methanol with water vapor, catalytic decomposition of ammonia, catalytic dehydrogenation of hydrocarbons, conversion of ferrosilicon with caustic soda and the like.

Of these known processes, water electrolysis, the reaction of methanol with water vapor, the catalytic decomposition of ammonia and the conversion of ferrosilicon with caustic soda relatively expensive. Large amounts of hydrogen are usually produced using the iron-steam process, by gasification of carbonaceous substances with water vapor and air and by conversion produced by hydrocarbon vapors or gases with water vapor. These procedures deliver but a hydrogen, which usually contains varying amounts of impurities such as carbon monoxide, Contains carbon dioxide, residual hydrocarbon gases, and the like. Although in many hydrogenation processes the remaining hydrocarbons are usually inert substances, they are undesirable in many cases. That Carbon monoxide is particularly undesirable because it is an active poison for the well-known hydrogenation catalysts, such as platinum, palladium, nickel and the like.

It is known that water vapor, CO ₂ and methane can be easily removed from hydrogen by adsorption. It is also known that the less easily adsorbing impurities in hydrogen, namely oxygen and carbon monoxide, can be converted into the easily adsorbable constituents water vapor and methane by catalytic hydrogenation and can then be removed in a known manner.

It was previously common to have carbon monoxide and hydrocarbon contaminants to remove from the hydrogen-containing raw gas by this one Shift reaction in which the carbon monoxide and hydrocarbon impurities reacted catalytically with steam to form hydrogen and carbon dioxide will. Usually about 90% conversion

Adsorption process

for cleaning technical hydrogen

and suitable for implementation

contraption

Applicant:

Union Oil Company of California,
Los Angeles, Calif. (V. St. A.)

Representative: Dr.-Ing. H. Ruschke, Berlin-Friedenau,

and Dipl.-Ing. K. Grentzenberg,
Munich 27, Pienzenauerstr. 2, patent attorneys

Clyde HOBerg, Long Beach, Calif. (V. St Α.),
has been named as the inventor

development of carbon monoxide reached. The gas treated in this way is then removed from carbon dioxide with the help of a known alkaline absorbents, such as sodium carbonate, sodium hydroxide solution, mono- or diethanolamine and the like, exempt. But because only about 90% of the carbon dioxide is converted here, it is practical CO-free, high-purity hydrogen only through repeated conversion and alkaline extraction under Use of up to three or four such separate treatment stages, i.e. using an involved expensive process to obtain.

According to the invention, an adsorption process for the purification of technical hydrogen is carried out by removing easily adsorbable impurities (water vapor, CO ₂ , CH ₄ ), the less easily adsorbable impurities, in a first of two separate adsorption zones, both of which contain moving layers of a granular adsorbent moved by gravity (CO, O ₂ ), which remained in the partially pre-purified hydrogen, are converted into methane and water vapor by hydrogenation at elevated temperature in a manner known per se, and the latter are removed in the second adsorption zone, whereupon those adsorbed in the first and second adsorption zones Components are desorbed and the adsorbent is recycled to the two adsorption zones. Preferably, the migrating layers from both adsorption zones are

909 730/433

agree before the adsorbed substances are desorbed. According to further preferred embodiments of the process according to the invention, the prepurified hydrogen is converted to 204 before the hydrogenation heated to 371 ° C and carried out in the presence of a platinum catalyst. A particularly preferred one The feature of the new process is that the product of per unit of time by the first adsorption zone of transported mass and specific heat of the pre-cleaned hydrogen is kept larger than the product of per unit of time transported through the first adsorption zone Mass and specific heat of the adsorbent and that the product from per unit of time by the second adsorption zone of transported mass and specific heat of the adsorbent is smaller is held than the product of per unit of time transported through the second adsorption zone Mass and specific heat of pure hydrogen.

In general, the gaseous mixture used as the starting product for the adsorption process according to the invention contains hydrogen in amounts of 80 to 90 percent by volume and also other gaseous constituents such as oxygen, carbon monoxide, nitrogen, carbon dioxide. Methane and other hydrocarbons and water vapor and the like. This gaseous mixture is passed into a first adsorption zone, in which it is mixed with a downward moving bed of solid, granular adsorbent, such as activated animal charcoal, activated aluminum oxide, silica gel or the like. is brought into contact. Highly activated vegetable charcoal (made from coconut shells, fruit kernels and the like) is preferably used. The more easily adsorbable components of the gaseous mixture, such as CH ₄ , CO ₂ and water vapor, are adsorbed, while hydrogen, carbon monoxide and possibly oxygen or nitrogen are not adsorbed. (The \ ^r One can also vary such that CO ₂ and water vapor are adsorbed while hydrogen, CO, N ₀ and methane remain unadsorbed and the latter is recovered later separated out.) It is then the loaded adsorbent containing the adsorbed components , indirectly heated and treated with a displacement gas, thereby forming an enriched gas product containing the desorbed components and leaving the hot, unloaded adsorbent. The non-adsorbed gases (hydrogen, CO and sometimes N ₂ , O ₂ and also methane) are removed from the first adsorption zone as the first lean mixture.

In the first adsorption zone - because of the relatively low concentration of hydrocarbons, CO ₂ and water vapor - a relatively small amount of solid granular adsorbent per unit volume of hydrogen-containing raw gas is required. The exothermic heat of adsorption, which is released in the first adsorption zone when the more easily adsorbed constituents are adsorbed, is transported upwards through the downward moving bed of adsorbent when - as is usually the case with this process - the product of per unit of time The mass transported through the first adsorption zone and the specific heat of the prepurified hydrogen is kept greater than the same product of the adsorbent, which move towards one another in the first adsorption zone. Under this condition, the heat of adsorption released is not carried downwards through the column by the moving bed of adsorbent which forms a sharp temperature gradient, but upwards by the non-adsorbed gases in the column, which are removed from it at temperatures between 65 and about 120 ° C.

The discovery of this phenomenon contributes to the effectiveness of the process of the invention and provides a substantial portion of the _{preheat necessary prior to the catalytic hydrogenation of the O 2} and C O impurities in the prepurified gas.

The first lean gas preheated in this way (ie the prepurified hydrogen) is additionally heated to about 204 to 371 ° C. and brought into direct contact with a platinum catalyst. A. Part of the hydrogen contained in the first lean gas stream is consumed in the catalytic hydrogenation with the formation of water vapor and methane. The catalytic hydrogenation of O ₂ , CO and CO ₂ residues is practically quantitative; the gas flowing out of the hydrogenation zone contains less than 5 parts per million CO and CO ₂ and consists essentially of hydrogen which is contaminated with methane and water vapor and possibly nitrogen.

This gas from the hydrogenation zone is heat exchanged with the first lean gas that enters the Hydrogenation zone enters, cooled, then by water cooling or the like. To about 40 ° C and then to cooled to a temperature of about 5 ° C. This cooled product of the hydrogenation zone constitutes the feed gas for the second adsorption zone and contains methane, water vapor and hydrogen, at times also nitrogen.

This cooled feed gas is countercurrently with a second downwardly moving Bed of solid, granular adsorbent brought into contact in such an amount that the water vapor, the methane and all more easily adsorbable components are selectively adsorbed. You get a second loaded adsorbent containing these substances and practically high purity hydrogen as a second lean gas. This gas product contains about 0.5 to 5.0 parts per million of residual CO and represents completely pure hydrogen. The stated level of CO contamination is far below that at which the known hydrogenation catalysts are poisoned.

Here in the second adsorption zone, the product of each unit of time is passed through the second adsorption zone transported mass and specific heat of the adsorbent kept smaller than the corresponding product of pure hydrogen. Those involved in the adsorption of methane and water vapor The heat released is transported upwards, with the gases being heated from around 5 to around 40 ° C the temperature at which the second lean gas, the pure hydrogen, is discharged from the process will. There is no sharp temperature gradient in the second adsorption zone. The one with the amount of the gases to be adsorbed and the degree of cooling that fluctuates during the adsorption process of the second feed gas is controlled so that the pure hydrogen is at about atmospheric temperature between about 10 and 45 ° C is withdrawn.

The second moving bed of the loaded adsorbent can be brought into countercurrent contact with a reflux gas of more easily adsorbable components such as CO ₂ , water vapor and the like

be, making adsorbed methane in handy

5 6

pure form as a gaseous by-product from the water vapor, into the shifting zone 12; can be desorbed here second adsorption zone. reacts under the temperature specified above (In a combined process in which the carbon and pressure conditions of the water vapor in counter hydrogen gases or vapors with water vapor are exposed to a catalyst (iron oxide) with CO, this by-product gas is used to form CO ₂ and further hydrogen. (Zone conversion zone recirculated and thus permits a 12, if necessary with the help of line 50 and 100% conversion of the hydrocarbons.) Valve 52 can be bypassed.) That from zone 12 - The two separate adsorption stages and the emerging Gas that contains only a few percent CO as an intermediate hydrogenation stage may internally be contaminated, will be passed through line 46 and halfway through pressure ranges. One io valve 48 and line 54 in the gas cooler 56 can be condensed at atmospheric pressure or below and at passes where a considerable part of the water vapor up to 56 or 70 kg / cm ² reaching pressures, separated in the separator 58 and there the pressures do not seem to be decisive. through line 60 with through valve 62 via which liquid hydrogen reacts easily in the presence of platinum level regulator 64, catalytic converters at the specified temperatures are drawn with 15 at a regulated rate. The cold and at least partially CO, CO ₂ and O ₂ itself at atmospheric pressure, and dehydrated hydrogen-containing gas then flows through the adsorptive separations of the hydrogen from line 66 and compressor 68. The pressures in CH ₄ , CO ₂ etc. and the CH ₄ of CO ₂ carried easily to the adsorption column are not crucial; at atmospheric pressure. At higher pressures (e.g. a pressure between normal pressure and 35 kg / cm ² or 7 kg / cm ² ) less adsorbent per unit 20 above that can be used. Expediently, the volume of gas supplied is required, the by-product gas supplying the pressure at or in the vicinity of the working pressures is required for the return of the gasification and conversion zone. The result is not to be appreciably compressed, and the primed (primary feed) gas is then in the whole process, at the same pressure the cooler 70 can be cooled down and through line 72 into the economically working. 25 first separation zone 16 of the adsorption column 14 ge

The two stages of adsorptive fractionation conducts.

can be carried out in separate adsorption columns through this adsorption column 14 constitutes a single one. With regard to the formation of perpendicular pressure-resistant apparatus is in the water and methane in the intermediate hybrid from top to bottom a zone undrierungszone for receiving, it has but as far expediently ₃₀ loaded adsorbent 74, a zone for But meadows, a particularly developed double cooling of the unloaded adsorbent 76, using a sorption column in the two separate zones for the release of high-purity hydrogen (the moving layers of the adsorbent with the "second lean gas") 78, a second adsorption first and the second feed gas in calming zone 80 a second gas feeding zone 82, a first come tion, after which the traveling layers of examples ₃₅ Hilfsrektifikationszone 84, a zone for releasing the adsorption zones are combined. This _{type of} by-product gas 86, a second mode of auxiliary rectification, is described in more detail with reference to the drawing, namely, operation zone 88, an auxiliary reflux gas supply zone 9Q, which is a schematic flow diagram. a zone prepurified to release water Wieaus the drawing can be seen, there is a preliminary material (the "first lean gas") 92, a first Adrichtung for carrying out the ₄₀ sorption zone 94 according to the invention, a main starting gas supply method in the main, from a gasification _zone 96 , a first main rectification zone 98, a zone 10, a conversion zone 12 and an ad reflux gas release zone 100, a main sorption column 14, which has a first adsorption zone rectification zone 102, a zone for releasing ad-16 and a second adsorption zone 20, sorted, hydrogen-free Gases 104, a zone between which there is a hydrogenation zone 18, in which 45 heating and desorbing of loaded adsorption, the gas flowing out of the first zone 16 is treated means 106, a displacement gas supply zone 108, and then the second zone 20 is fed. an adsorbent collection zone 110 and a Bo-Das serving for the production of hydrogen denzonell2 are arranged. These devices with the starting material is passed through line 22 (by _the circulation of a granular adsorption valve 24) a controlled rate in the comparison that initiated within the column as Wandergasungszone 10 ₅₀ means. If a carbon layer is moved, feed lines for the substance to be purified or hydrocarbon-containing substance as gasifiable lowing gases and discharge lines for the treated starting material is used, an adsorption column provided with acidified gases is filled with inventive gas through line 26 (through valve as per this characterized in that they are introduced in two 28) regulated speed. Through 55 superimposed, separate zones 16, 20 under line 30 with valve 32, water vapor is distributed, with it being passed through the second zone 20 for the purpose. Line 34 with valve 36 enables the admission of the first zone 16 with adsorption guidance of the pipe 114 which may be led out of the second adsorbent means that the methane desorbed through the first ion zone. Pipes 116, 118 led below zone 16 above are used to remove the specified temperature and pressure conditions 60 adsorbents from the second zone 20 and a gaseous mixture is formed in the gasification zone 10 that between the first and second zones is a mixture of hydrogen and oxygen , Carbon monohydrogenation reactor 18 is connected. Oxide, carbon dioxide, methane and higher molecular weight The hydrocarbons and water vapor supplied at the top of the adsorption column and, in the case of granular adsorbents, also run downwards through the column using air as the oxygen-containing gas. Immediately above said zone 78 contains nitrogen. the cold, unloaded adsorbent is split into two The unclean, hydrogen-containing gas flows through streams. The first adsorbent flow line 38 with (by valve 40) regulated run through the main pipe 114 downwards through the speed, optionally together with from the line second separation zone 20, without touching it, additional 70 fed directly to the line 42 via valve 44 into the first separation zone 16. The second adsorption

Medium flow runs directly through zone 78 and second separation zone 20 and then through secondary pipes 116 and 118 down through first separation zone 16 without touching them. The two separate adsorbent streams are then combined just above the main rectification zone 102 and flow down therefrom combined. Of course, a variety of main and secondary pipes can be used; the number depends on the amount of adsorbent.

The hot, unloaded adsorbent is withdrawn from the soil zone 112 with the aid of the regulator 124 to such an extent that a practically constant adsorbent level in the soil sun 112 is maintained. The withdrawn adsorbent reaches the vessel 128 via the closure leg 120 with the control valve 122 and the line 126 , from where it is transported by means of a transport gas via the line 136 into the separator 138 ; there the gas is separated from the solid particles; the latter flow back through line 140 into zone 74 . The transport gas is fed to the vessel 128 by means of a blower 130 through the line 132 (with valve 134); After separation from the solid particles, the transport gas flows back to the blower 130 through the lines 142 and 144. As will be explained further below, its volume is constantly increased by the supply of a "cleaning gas"; therefore a line 146 with valve 148 is provided through which this excess gas portion can be discharged.

Compressed, cooled, impure hydrogen-containing primary feed gas is passed through line 72 into the first exit gas feed zone 96 and countercurrently passes upwards through the downward moving layer of adsorbent in the first adsorption zone 94. Here, carbon dioxide, water vapor and methane and the more easily adsorbable components are adsorbed , whereby hydrogen, oxygen, optionally nitrogen and carbon monoxide, remain practically unadsorbed. This “pre-cleaned hydrogen” (first lean gas) is discharged from the first release zone 92 through line 150 and passed into the hydrogenation zone 18 . The first loaded adsorbent passes down into the first main rectification zone 98, where it is brought into contact with a return _{gas which contains CH 4} , CO ₂ , water vapor and more easily adsorbable components, with residual traces of components of the first lean gas preferably being desorbed and a first rectified adsorbent is produced. The desorbed components rise and combine with the first lean gas. The first rectified adsorbent is then treated in the main rectification zone 102 where the return gas is desorbed. The first lean gas flowing through line 150 is substantially preheated by absorbing the exothermic heat of adsorption that has been released in the first adsorption zone 94 . This preheated gas is then passed through the preheater 152 and heated to about 260-370 ° C. The heated gases flow through line 154 into the hydrogenation zone 18, where a catalytic hydrogenation of CO, CO ₂ and O ₂ - if any - takes place. Some of the gases flowing out of the hydrogenation zone can be passed through the hydrogenation zone again in order to further reduce the CO content. The gases pass through line 156 to cooler 158 where they are cooled to about 5 ° C. The cooled gases then flow through line 160 into separator 162, from which condensate is withdrawn through line 164 (controlled by valve 166 ). The cooled, dehydrated gas from the hydrogenation zone, which contains hydrogen, methane, optionally N ₂ and traces of water vapor, then passes through line 168 as the second starting gas to the second gas supply zone 82.

This second exit gas flows upwardly from the feed zone 82 through the second adsorption zone 80 in countercurrent with the downwardly moving adsorbent. All components of the gaseous mixture that are more easily adsorbable than hydrogen are adsorbed with the formation of a second loaded adsorbent and leave behind practically pure hydrogen ("second lean gas") or a hydrogen-nitrogen mixture if nitrogen is present. A portion of this pure hydrogen-containing product is withdrawn from the release zone 78 through line 170 at a rate controlled by the regulator 172. The remainder of the unadsorbed gas flows up through the cooler 76 as the aforementioned purge gas and serves to desorb traces of adsorbed displacement gas from the hot, unloaded adsorbent which is cooling therein. This purge gas is combined with the pumped transport gas stream and an equal amount is removed therefrom through line 146 and combined with the hydrogen lean gas product in line 170 .

The product gas containing pure hydrogen leaves the release zone 78 at about 40 ° C., to which it has been heated by the heat of adsorption released.

The second loaded adsorbent is brought into contact in countercurrent with a more easily adsorbable _{reflux gas, which contains CH 4} , in the first auxiliary rectification zone 84 , whereby preferably remaining adsorbed hydrogen is desorbed and a second, partially rectified adsorbent is formed and the desorbed hydrogen is formed with the non-adsorbed lean gas flowing through the second adsorption zone 80 is combined.

The adsorbent thus rectified then passes into the second auxiliary rectification zone 88 in which it is brought into contact with an auxiliary reflux gas supplied through line 174 at a rate controlled by temperature controller 178 in response to thermocouple 180 by valve 176. The more easily adsorbable auxiliary srückflußgas desorbs preferably the adsorbed methane formed in the hydrogenation zone 18 in addition to such methane that may have been contained in the first lean gas that was withdrawn from the first separation zone 16. Some of the methane desorbed flows upward into the first auxiliary rectification zone 84 as return, while the remainder can be discharged as by-product through line 182 at a rate controlled by temperature controller 186 as a function of thermocouple 188 by means of valve 184 via valve 190.

The fully rectified second adsorbent stream travels down from the bottom of the second auxiliary rectification zone 88 through tubes 116 and 118 to be combined with the first adsorbent from zone 16 in the main rectification zone 102 . Here the granular adsorbent is _{adsorbed in countercurrent with a CO 2} , water vapor and sometimes CH ₄ and possibly more easily.

Claims (8)

I 07S566 brought into contact return gas containing bare components, which serves to desorb the above-mentioned, somewhat less easily absorbed auxiliary return gas, part of which flows into the rectification zone 98, while the remainder passes through line 174 into the second auxiliary rectification zone 88. The combined rectified adsorbent then passes down the tubes of the heating and desorbing zone 106, where the adsorbent ίο is heated indirectly and directly with a displacement gas, e.g. B. water vapor, is brought into contact. The displacement gas flows upward in countercurrent to the adsorbent and desorbs residual adsorbed hydrogen-free gases that collect in the release zone 104. Some of these gases flow as a return into the main rectification zone 102, while the remaining part is discharged through line 196 at a rate controlled by temperature controller 200 as a function of thermocouple 202 by means of valve 198. The desorbed gas is cooled and the water vapor is condensed. The hot, unloaded adsorbent is then returned to the top of column 14 where it is cooled, split into first and second adsorbent streams, and again passed through the first and second adsorbent zones. Of course, the mode of operation of the adsorption process can be varied in many ways. The following values are given as an example of the process according to the invention. Example 35 Natural gas with a methane content of about 90% is reacted with water vapor to produce hydrogen and carbon monoxide. The natural gas is mixed with water vapor in an amount of 2.5 mol of steam per mol of methane, which corresponds to a 150% excess. The pressure is 7.7 kg / cm2 and the outside temperature of the system is 790 ° C. A nickel catalyst on a carrier is used to accelerate the conversion between methane and water vapor. A supported platinum catalyst can also be used. The gas flowing out of the system has the following composition in the dry state: Table 1 Ingredient Mol percent hydrogen 70.5 Carbon monoxide 16.6 Carbon dioxide 6.8 Methane 6.1 100.0 55 60 If necessary, this gas is mixed with further water vapor in order to To bring the ratio of water vapor to carbon monoxide to a value of 1.0. The gaseous mixture undergoes a shift reaction at a pressure of. Subject to 7 kg / cm2. The reaction is accelerated by a supported iron oxide catalyst and the outlet temperature is kept at 415 ° C. The product of the conversion has the following composition in the dry state: Table 2 Constituent part mol percent hydrogen 75.0 Carbon monoxide 1.8 Carbon dioxide 17.7 Methane 5.5 100.0 It is cooled and freed from condensed water. The cooled product is compressed from about 6.3 to about 8.4 kg / cm 2 and further cooled and passed into the first adsorption zone of the adsorption column 14. The carbon dioxide, the water vapor and part of the methane are adsorbed on the first adsorbent stream, with the hydrogen, the greater part of the CH4 and a smaller part of the CO2 ("first lean gas") remaining unadsorbed. The latter gas is heated to 315 ° C and passed through the C O hydrogenation zone in the presence of a supported platinum catalyst, where CO and CO2 are quantitatively hydrogenated to methane; the outflowing product is cooled to 50C and brought into contact with the adsorbent in the second adsorption zone, producing highly purified hydrogen ("second lean gas"). The three gas products from the selective adsorption column have the following compositions: Table 3 Ingredient Lean gas from line 170Mol percent gas by-product from line 182Desorbed gas from line 196Hydrogen .... carbon monoxide, 4 parts per million methane carbon dioxide ..1002.0 94.5 3, 51.6 98.4100100100 The by-product gas, which contains a higher methane concentration than the starting gas, is returned to the conversion plant 10 at a pressure of 8.8 kg / cm2 to be combined with fresh starting material to produce additional amounts of hydrogen. Activated coconut shell charcoal was used as the granular adsorbent. P AT IiNT AXSP R t'CHE-. 1. Adsorption process for purifying technical hydrogen, characterized in that in a first of two separate adsorption zones, the two moving layers of a granular adsorbent moved by gravity, easily adsorbable impurities (water vapor, CO ₂ , CH ₄ ) are removed that the less easily adsorbable impurities (CO, O ₂ ), which have remained in the partially pre-purified hydrogen, are converted into methane and water vapor by hydrogenation at elevated temperature in a manner known per se and that the latter are removed in the second adsorption zone, whereupon those in the first and Second adsorption zone adsorbed components are desorbed and 909730/433 the adsorbent is recycled into the two adsorption zones. 2. The method according to claim 1, characterized in that the moving layers from both adsorption zones be combined before the adsorbed substances are desorbed. 3. The method according to claim 1 or 2, characterized in that the pre-purified hydrogen heated to 204 to 371 ° C prior to hydrogenation. ίο 4. The method according to claim 1 to 3, characterized in that the hydrogenation in the presence a platinum catalyst is made. 5. The method according to any one of claims 1 to 4, characterized in that the product of each Unit of time through the first adsorption zone transported mass and specific heat of the pre-cleaned Hydrogen is kept greater than the product of per unit time by the first Adsorption zone of transported mass and specific heat of the adsorbent. 6. The method according to any one of claims 1 to 5, characterized in that the product of each Unit of time transported through the second adsorption zone and the specific heat of the Adsorbent is kept smaller than the product of per unit of time through the second adsorption zone transported mass and specific heat of pure hydrogen. 7. The method according to claim 1, characterized in that methane from the in the second adsorption zone loaded adsorbent is desorbed as a gaseous by-product of the process will. 8. Apparatus for carrying out the method according to the preceding claims, consisting of an adsorption column with devices for circulating a granular adsorbent which moves within the column as a moving layer, supply lines for the gases to be cleaned and discharge lines for the treated gases, characterized in that the column is divided into two superimposed separate zones (16, 20), a pipe (114) being passed through the second zone (20) for the purpose of loading the first zone (16) with adsorbent, which pipe leads through the first zone (16) Pipes (116, 118) serve to remove the adsorbents from the second zone (20) and that a hydrogenation reactor (18) is connected between the first and the second zone. Considered publications:
German Patent No. 558 430;
Austrian Patent No. 48 238;
British Patent No. 365 092;
U.S. Patent Nos. 2,647,587, 2,747,970 . 1 sheet of drawings © 909 730/433 2.60